U.S. patent number 4,498,390 [Application Number 06/299,262] was granted by the patent office on 1985-02-12 for method and apparatus for embossing foil.
This patent grant is currently assigned to Philip Morris Incorporated. Invention is credited to James A. Bowling, Wallace M. David.
United States Patent |
4,498,390 |
Bowling , et al. |
February 12, 1985 |
Method and apparatus for embossing foil
Abstract
A method and apparatus for embossing foil to produce warp-free,
textured packaging sheet. The method comprises the forming of
bosses in the foil while firmly supporting the foil clamped on
rigid lands at the perimeter of the boss to be formed. Drawing the
foil between rigid male and female walls of a forming cavity while
so held, and interposing a sheet of yieldable material between the
surface of the female portion of the cavity and the sheet of foil
to produce a yieldable matrix against which the foil comes to
rest.
Inventors: |
Bowling; James A. (Midlothian,
VA), David; Wallace M. (Richmond, VA) |
Assignee: |
Philip Morris Incorporated (New
York, NY)
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Family
ID: |
26845746 |
Appl.
No.: |
06/299,262 |
Filed: |
September 3, 1981 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
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148316 |
May 9, 1980 |
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Current U.S.
Class: |
101/365;
101/6 |
Current CPC
Class: |
B21D
13/04 (20130101); B29C 53/22 (20130101); B31F
1/07 (20130101); B31F 1/26 (20130101); B31F
2201/0723 (20130101); B31F 2201/0717 (20130101); B31F
2201/0743 (20130101); B31F 2201/0756 (20130101); B31F
2201/0758 (20130101); B31F 2201/0764 (20130101); B31F
2201/0784 (20130101); B31F 2201/0738 (20130101) |
Current International
Class: |
B21D
13/00 (20060101); B21D 13/04 (20060101); B29C
53/22 (20060101); B29C 53/00 (20060101); B31F
1/00 (20060101); B31F 1/26 (20060101); B31F
1/07 (20060101); B31F 1/20 (20060101); B41F
031/02 () |
Field of
Search: |
;101/365,6
;156/161,163,164,167,220,219 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Apley; Richard J.
Assistant Examiner: Isabella; David
Parent Case Text
CROSS-REFERENCE
This is a continuation of Ser. No. 148,316, May 9, 1980, now
abandoned
Claims
What is claimed is:
1. A method of embossing a sheet of metallic foil in at least one
pair of complementary embossing dies having male and female die
portions comprising:
a. providing a sheet of compressible deformable material;
b. layering said compressible deformable sheet with a sheet of said
metallic foil;
c. placing said sheets between said male and female die portions
with the metallic foil surface facing the male die portion
d. bringing said die portions together under pressure with male and
female portions in register to compress said metallic foil against
a surface of a die portion with yieldable force.
2. The method of claim 1 further comprising:
a. providing clamping means for holding foil immobile against
lateral movement adjacent the perimeter of said individual die
portions; and
b. clamping areas of said foil adjacent the perimeter of said
individual die portions while pressing said foil within said dies
for embossing said foil.
3. The method of claim 1 wherein the metallic foil face is pressed
against by the male portion of said pair of dies and said
compressible-yieldable sheet is pressed into the female portion of
said set of dies.
4. The method of claim 1 wherein said layer of foil is laminated
and bonded to said compressible deformable sheet.
5. The method of claim 1 wherein said foil is a metallic coating on
a surface of said compressible deformable material.
6. A method of embossing sheets of metallic foil in at least one
pair of embossing rolls having complementary pairs of male and
female dies in the respective surfaces thereof comprising the steps
of:
a. providing a first roll of a given diameter with female cavities
in the surface thereof,
b. providing a second roll of a smaller diameter than the first
roll and with male die portions complementary to the female die
cavities in the said first roll,
c. providing means for driving said first and second rolls while in
yieldable contact at a nip therebetween at different relative
surface speeds so as to cause accurate register of said male die
portions on said second roll with respective female die cavities on
said first roll,
d. passing said sheet of foil through the said nip of said first
and second rolls to emboss said foil,
e. providing a sheet of yieldable non-metallic material,
f. layering said non-metallic yieldable material with said foil and
passing the layered combination through the nip of said rolls with
the metallic foil surface facing said male portions of said second
roll.
7. A method as in claim 6 wherein at least one of said rolls is
heated.
8. A method of embossing a prelaminated material including a foil
layer and a buffer material layer comprising the steps of:
providing a female embossing roller having cavities formed in the
surface thereof, said cavities being arranged to define a
preselected pattern;
providing a male embossing roller having bosses protruding from the
surface thereof, said bosses being arranged to be complementary to
said cavities and to meet in registry therewith;
orienting said female embossing roller and said male embossing
roller to provide a preselected clearance therebetween, said
clearance being sufficient to effect embossing of the prelaminated
material positioned therebetween;
feeding the prelaminated material between the rollers with the foil
layer positioned between said male embossing roller and the buffer
material layer.
9. A method of embossing a foil material comprising the steps
of:
providing a female embossing roller having cavities formed in the
surface thereof, said cavities being arranged to define a
preselected pattern;
providing a male embossing roller having bosses protruding from the
surface thereof, said bosses being arranged to be complementary to
said cavities and to meet in registry therewith; providing a buffer
material;
orienting said female embossing roller and said male embossing
roller to provide a preselected clearance therebetween, said
clearance being sufficient to effect embossing of the foil material
and the buffer material positioned therebetween;
feeding the foil material and the buffer material between the
rollers with the foil material positioned between said male
embossing roller and the buffer material.
Description
BACKGROUND OF THE INVENTION
Textured foil of the type to which this invention applies is used
in packaging of commodities and appears most often in the make-up
of retail packages. An example of this type of foil is found in
packages designed for marketing of cigarettes. The metallic part of
the foil forms an excellent vapor barrier and is desired for this
purpose as well as for wrapping and adding attractiveness to the
appearance of a pack of cigarettes. In the operation of cigarette
packaging machinery it is usual to advance a foil-paper laminate
into the equipment at a rate sufficient to supply each pack of
cigarettes with the amount of foil necessary to make up a given
package. The foil component is combined cooperatively with other
components to make up a complete cigarette pack containing a
standard number of cigarettes. The package is overwrapped and
sealed to make it air tight then placed in a carton.
The prior art devices for processing the foil to emboss it comprise
texturing rolls which are of cooperating complementary male and
female die members arranged to rotate into register for forming
bosses in the foil at the nip of the forming rolls. In one such
device, the pair of rolls consist of one roll made with rigid male
forming plugs. This is caused to run in compressive contact along a
nip line against a roll surface with a resilient polyurethane
covering. The foil is pressed into the yieldable surface of the
polyurethane covered roll by the male forming bosses to form bosses
in the foil.
These above methods are widely used in cigarette making and
packaging machinery, but an inherent problem associated with the
feeding of the textured foil is caused by the tendency of the
textured foil made by former methods to curl and cause it to be
difficult to guide through automatic machinery. Tendency to curl
requires that more highly engineered guide and control features be
provided than for a foil which lies flat. A flat foil will advance
a greater distance through packaging machinery without the need for
excessive guiding and controlling apparatus specially made for the
express purpose of keeping the foil flat while it is manipulated in
automatic handling.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a method for
embossing a sheet of foil to produce a textured sheet relatively
free of an inherent tendency to curl.
It is a further object of the present invention to provide
apparatus for implementing the above method of this invention.
The present invention achieves the production of relatively
curl-free textured foil by embossing the foil while localizing the
effects of lateral dimensional deformation in the foil to the
immediate surface area of each individual boss. By this is meant
that in drawing the foil to produce an individual boss, the
surrounding perimeter about the base of the boss is held in place,
stabilized dimensionally, and is maintained so while the final
drawing of the boss takes place. A male die in contact with the
foil presses against the foil to drive and draw it into a
complementary rigid walled female die to form the boss. The
yieldable material is made to interlie the opposite surface of the
foil and the surface of the female portion of the forming die. The
yieldable material deforms uniformly along with the foil being
drawn to provide a cushioned surface mating area between the
surface of the foil and the walls of the female die.
The compressive characteristics of the yieldable material are such
as to distribute the compressive forces uniformly over the stressed
area of the foil under contact for drawing it into conformity with
the general form of the walls of the individual female die
cavities. Thus the foil is relatively unimpeded in its freedom to
deform yet is resiliently and forgivingly supported in the desired
final configuration between the forming members. In this manner
only that area of foil which is included within the perimeter of
each boss is apt to be affected in lateral dimension while being
drawn to form a particular boss. A minimum of curling is thus
imparted to the rest of the sheet of foil as embossing action
proceeds. Since the drawing action for each boss is localized, an
uneven lateral distention of the bulk of the sheet of foil is held
to a minimum.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a side view in elevation showing a pair of embossing
rolls and buffer material and foil feed bobbins.
FIG. 2 is a side view in elevation showing the embossing rolls of
FIG. 1 and a feed bobbin of prelaminated foil.
FIG. 3 is a view in elevation showing an enlarged detail of the
embossing rolls of FIGS. 1 and 2.
FIG. 4 is an enlargement of a single pair of embossing dies with
foil in place.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring now more particularly to the drawings and specifically to
FIGS. 1-4 thereof, the apparatus of FIG. 1 includes rotatable
supply rolls or coils 10 and 12 commonly referred to as bobbins in
cigarette manufacturing nomenclature. Bobbin 12 carries a supply of
a metallic foil 18, such as aluminum foil, in strip form of a width
suitable to a pre-selected use, and bobbin 10 carries a supply of
resilient or deformable buffer material 20, such as paper or
plastic sheet material. The metallic foil may be of a range in
thickness of from 0.001" to 0.030" and of a surface quality
preselected to produce a desired effect after embossing. The
thickness of the buffer material 20 may vary in thickness of up to
ten times the thickness of the foil as is found to be best by
experiment for a particular foil thickness.
While the present invention will be described as being applied to
embossing of metallic foil, and particularly for cigarette
packaging, it will be understood that the material to be embossed
may be used for any purpose and may be made of any ferrous or
nonferrous metal or combinations thereof. Plastic or paper
materials to which a metallic coating has been applied may also be
used. It is also contemplated that the present invention may be
practiced in connection with the use of heat applied directly to
the foil by suitable means such as infrared, hot air or other
heating means not shown to facilitate and enhance embossing action.
Heat may be applied directly to the material as stated above or by
heating of the embossing rolls 14 and 16 in some conventional
fashion of heating, not shown herein.
The foil material 18 to be embossed is shown as coiled in FIG. 1 on
bobbin 12 from which it is fed layered with the resilient buffer
material 20 from bobbin 10 into the nip of a pair of tangential
embossing die rollers 14 and 16, the impression roller 14, and the
embossing roller 16. Both rollers are made of relatively hard
material. The rollers 14 and 16 are driven by suitable means, not
shown, to rotate in the direction of the arrows shown in the
drawings. The foil 18 and the buffer material 20 pass between the
rollers 14 and 16 to pressure-form the foil 18. Take-up rollers 24
and 22 receive and store the embossed foil 28 and the spent buffer
material 26 respectively.
FIG. 2 illustrates the use of a prelaminated foil 34 being drawn
from feed bobbin 13. Laminate 34 includes a layer of foil 18 and a
layer of buffer material 10 which may remain laminated subsequent
to embossing as illustrated in FIG. 2 as well as in FIG. 3 and FIG.
4.
As best seen in FIG. 3 and 4, the foil 18 is extruded or drawn into
the female cavity 30 of the female impression roller 14 by the
raised boss portion 32 of the male embossing roll 16.
The depressed portions are made of the configuration designed to
result in the particular decorative and structural effect intended
for a particular purpose.
Particular care is taken in preparing the embossing rolls to
guarentee that a non-curling foil is produced at their nip. In
order to achieve this, it is critical that very accurate register
is had between the individual bosses and their complementary female
recesses.
The embossing rolls are made of different diameters with the male
projections on the smaller roll. The use of a roll of smaller
diameter to carry the male die portions is found to achieve
improved results over rolls having equal diameters.
In preparing a pair of rolls, first a steel roll, preferably the
smaller roll, is machined or etched with the desired pattern as
represented in multiple arrangements of male bosses which protrude
from the surface uniformly about the periphery of the roll 16. The
smaller roll is then hardened and tempered. A second roll 14 of
larger diameter is prepared with a uniformly ground smooth surface.
The rolls are then mounted with their axes in a common plane and
means, not shown, are provided for causing the two rolls to meet at
the nip under pressure. The two rolls are rotated under controlled
pressure contact until the pattern of male protrusions on the
smaller roll is duplicated in complementary recesses impressed in
the surface of the larger roll.
In order to guarantee continued perfect register, registration
constancy zones, not shown, which act like gear drive teeth are
provided about the roll peripheries for a short distance inwardly
from the ends of the rolls. These consist of areas of repetitively
duplicated bosses and recesses which provide the equivalent of a
gear toothed drive and which resemble an embossing pattern but
which are individually much larger than the bosses and recesses of
the embossing pattern. They act as a very fine toothed drive
mechanism in which back-lash is practically eliminated, and driving
noise and vibration are held to a minimum.
Extreme care is exercised in transferring the patterns on the
embossing and driving male roll to the surface of the female roll.
The relative diameters of the rolls are calculated to insure that
the circumferences of the separate rolls are such that the male and
female portions match evenly with no gaps or improper matching and
registration of any set of recesses.
In practice, the foil laminate is fed into the nip of the rolls at
high speed and is driven through while receiving the desired
impression of the pattern as designed. As stated above, a suitable
set of apparatus of conventional design for applying spring
pressure, not shown, is provided for maintaining adjustably a range
of desired pressures for urging the rolls into contact at the
nip.
Referring now to FIG. 3, it will be seen that the laminate 34 is
advanced in the direction of the arrow to interlie the bosses and
recesses of the nip of the rolls 14 and 16. The inner wall of the
recess 30 is shown as receiving the yieldable portion 20 of the
laminate 34 which is compressed within the nip provided at the line
of greatest proximity of the boss 32.
The progressive action of clamping at the perimeter of the boss to
be formed and subsequent drawing of the foil while being advanced
through the nip between the circumferentially disposed lands 31 and
33 of the rolls between the recesses, together with the localized
drawing action on the foil by the constantly reducing separaton of
the mating bosses 32 and recesses 30 as rotation proceeds, limits
the deformation of the foil area to the local area of the
individual bosses.
As stated, this yieldable clamping and drawing action results in
localized deformation of the foil. In effect this establishes the
raised pattern without substantially aberrating the uniformity of
over-all lateral displacement of the sheet of foil area-wise during
the drawing of the individual bosses therein. The foil is thus
protected against undue non-uniform stress area-wise and physical
damage at each boss by presence of the yieldable layer 20 which
cushions and protects the foil against harsh compressive massaging
of a damaging sort.
In this fashion, a relatively curl-free sheet is produced which can
more accurately and conveniently be fed through package forming
machinery with a minimum of problems which normally are associated
with curling of the foil.
Having described the preferred mode of carrying out my invention
and bearing in mind that this description is to be considered for
illustrative purposes without limiting the scope of my invention to
the disclosure made herein,
* * * * *